Heat exchangers are used in a wide variety of applications and come in a wide variety of configurations to fit these various applications. A typical heat exchanger uses a fluid transporting unit or tube portion operable to transport a fluid therethrough, such as heat conducting tubing arranged in a sinuous configuration, and a plurality of heat conducting fins (fin bank) in heat conducting contact with the tube portion. One fluid flows through the tube portion and another fluid flows along the outer surface of the tube portion between the fins thereon to transfer heat between the two fluids. Typically the tube portion is arranged in a sinuous configuration with substantially straight segments being interconnected by connecting segments (typically semicircular segments) so that the fluid flowing within the tube portion passes through the fin bank a desired number of times. Due to the differing applications that the heat exchangers are used in, the heat exchangers will come in a variety of shapes that require fins having differing quantities of columns of openings that the straight segments pass through.
The fins are typically stamped from a sheet of heat conducting material with a die configured to produce a plurality of columns of openings in the sheet for each stamp of the die (i.e., 2, 3, 4, etc. columns per stamp). The number of rows of openings in each column is determined by the height of the sheet of heat conducting material from which the fins are stamped (i.e., the sheet can have a height that yields 2, 3, 4, etc. rows of openings per stamp of the die). To make the heat exchanger more compact, the dies are configured so that the openings in each column overlap the openings in an adjacent column formed in the same stamp of the die. With this configuration, however, a straight line cannot be drawn between adjacent columns formed from the same stamp of the die.
To accommodate tube portions requiring fins having more columns than the die can produce in a single stamp, the sheet is stamped multiple times to produce a desired number of columns of openings. Thus, a two column die can be used to make fins having two columns of openings or multiples thereof (i.e., 4, 6, 8, etc. columns). Likewise, a three column die can be used to make fins having three columns of openings or multiples thereof (i.e., 3, 6, 9, etc. columns). When making fins that require the die to stamp the sheet of heat conducting material multiple times to produce each fin, however, the spacing between the adjacent columns formed in different stamps of the die is larger than the spacing between the adjacent columns formed in the same stamp of the die due to the overlapping nature of the openings in adjacent columns formed in the same stamp of the die. For example, in a fin having six columns of openings formed from a die capable of producing two columns of openings per stamp, the spacing between columns two and three will be greater than the spacing between columns one and two and between columns three and four. Likewise, the spacing between columns four and five will be greater than the spacing between columns three and four and between columns five and six. This additional spacing is necessary to provide a straight line between tube columns three and four and between columns five and six to allow a cut to be made between the tube columns.
Due to this extra spacing between adjacent columns formed from different stamps of the die, the arrangement of the straight and interconnecting segments of the fluid transporting unit are spaced apart at different dimensions to accommodate the spacing of the columns of the fin. This extra spacing can increase the overall size of the heat exchanger thereby not making efficient use of the available space in which the heat exchanger is to be used. Additionally, this spacing increases the complexity of forming the tube portion due to the necessity of ensuring that the various segments align with the spacing of the columns in the fin which increases the cost of producing the heat exchanger. Thus, it would be advantageous to produce a fin that can be made with any desired number of columns while being compact to enable efficient use of the available space. It would also be advantageous to produce a fin having any desired number of columns of openings that can be used on a tube portion without requiring differing spacing of the segments of the tube portion to accommodate differing spacing between columns of openings in the fin.